1. Field of the Invention
The present invention relates to a tab member especially for use as a "nontouch" grip for applying a dressing comprising an adhesive layer and optionally a release liner to the skin without touching the adhesive layer, a method for manufacturing such tab member and a dressing comprising the tab member.
2. Description of Related Art
As it is commonly known thin wound dressings are difficult to apply to wounds, especially in curved areas, without wrinkling or sticking to themselves or to the users, e.g., a nurse or assisting persons fingers. It is desirable to apply all kinds of dressings without touching the adhesive layer in order to avoid reducing the adhesiveness. Because of the risk of introducing bacteria to the wound it is desirable to apply a dressing to a patient's skin without touching the surface of the dressing that is to come into contact with the skin. The prior art discloses several methods for facilitating handling of a wound dressing.
GB Patent APPLICATION 2,128,479 describes a surgical dressing having two release sheets, each covering half of the dressing and having a free edge curved at the center of the dressing. As the curved edges of the release sheets are peeled back, the center of the dressing is applied over a catheter or to a wound, followed by the ends, thereby preserving sterility by eliminating the need to touch the adhesive surface of the dressing.
U.S Pat. No. 4,753,232 discloses a "handle" portion along one edge of the dressing. After the dressing is applied, the handle may be removed by tearing, or it may carry an adhesive coating so that it may be adhered to the skin of the patient.
Another known method of avoiding contact with the edges of a bandage by fingers or forceps is disclosed in U.S. Pat. No. 4,646,731 disclosing a bandage which is coated with an adhesive and the edges of which are protected by a pair of folded V-shaped tabs. After removing the backing sheet from the bandage, one tab is removed and the corresponding end of the bandage is applied to the skin. The second tab is grasped and removed as the entire length of the bandage is then applied.
European Patent Application No. EP 0 168 174 discloses a dressing comprising a first adhesive contact layer and an inner surface of a thin film backing. A release layer covering the first adhesive layer is removed prior to application of the dressing, and the film backing preferable has an edge portion free of adhesive to facilitate the removal of the release layer from the dressing without touch conlaminating the underside of the dressing. A relatively rigid carrier section is secured to the outer surface of the film backing by a second adhesive layer, and the carrier section includes rigid handles keeping the dressing extended during application of the dressing to a skin surface and prevents the dressing from curling or folding up.
U.S. Pat. No. 4,744,355 discloses a solution to a problem associated with excessive peeling force during removal of backings from wound dressings by dividing the release liner in halves. A wound dressing is disclosed in which the release liner halves are each divided into a release liner main body and a release liner edge strip. The release liner main body overlaps a portion of the edge strip and the two are secured to each other by a flexible hinge. As the release liners are pulled away from the wound dressing, the hinge means are employed, thus reducing the peeling force.
U.S. Pat. No. 5,106,629 discloses a dressing having a thin transparent film layer, a stable backing layer over the outer surface of the transparent layer, and a release liner. The backing layer and the release liner each have a corner tab to facilitate the peeling of each from the transparent layer.
Published EP APPLICATION No. EP 0 630 629 discloses a flexible wound dressing product that includes a thin-film layer, an adhesive layer, a backing layer which may be porous, an optional support layer, an optional release liner, and a hydrogel material without the use of an adhesive. The wound dressing may also include a removable V-shaped tab interposed between the thin film layer and release liner, providing a grippable surface for the removal of the release liner from the transparent thin film layer and to facilitate the handling of said wound dressing during application of the dressing to the wound.
GB Patent Application, No. 2 224 445 A discloses an adhesive dressing which comprises a backing layer having a pressure sensitive adhesive layer over one surface thereof, a removable protector which covers the adhesive layer and extends beyond the backing layer at one or more edges and a conformable support layer which is reversibly attached to the non-adhesive surface of the backing layer and extends beyond the backing layer at one or more of the edges. Said protector comprises first and second parts, the first part having a portion extending away from the adhesive surface and bent back to form a V-shape and the second part having a portion extending away from the adhesive surface and overlying the V-shaped first part.
Published International Application No. WO 94/14393 discloses an adhesive dressing comprising a backing layer, a pressure sensitive adhesive thereon and a support layer attached to the non adhesive surface of the backing layer. The dressing is characterised in having an additional edge strip component on the adhesive surface to facilitate application of the dressing to the skin. A removable protector covers the adhesive layer and extends beyond the backing layer. The removable protector may be divided into two or more pieces, of which the smaller one may be folded into a V-shaped handle.
European Patent Application No. EP 0 630 629 describes a hydrogel wound dressing product which includes a thin film layer, an adhesive layer, a backing layer which may be porous, an optional support layer, an optional release liner, and a hydrogel material. The wound may also include a removable tap interposed between the thin film layer and release liner, providing a grip surface for the removal of the release liner from the transparent thin film layer and to facilitate the handling of said wound dressing during application of the dressing to the wound.
A problem associated with the state of the art dressings provided with V-shaped tab members in order to provide a "non-touch" grip for applying the dressing comprising an adhesive layer and a release liner to the skin is that a wide area with an undesired air channel is created in front of the edge of the tab member being positioned across the dressing.
The wide area with an air channel is created partly during manufacturing of a dressing product having an incorporated V-shaped tab member and partly during storage. When manufacturing the V-shaped tab member by bending the area of the bending zone is subjected external forces which will give rise to an internal stress-situation in said area. Prior art V-shaped tab members being bent is seen to have a certain amount of stored stresses. The outer tip of the fold will be influenced by tensile stresses, and the inner tip of the fold will be influenced by compressive stresses. Together these stresses will force the two flaps of the V-shaped tab member from one another, once the dressing product is produced and stored. This spreading effect of the flaps may cause the area of the adhesive layer to detach along the line of bending of the two flaps from the release layer, enabling air to enter between the two said layers and turning the area into an unwanted air channel.
A further problem in conventional V-shaped tab members is that the tensile stresses in the outer tip of the fold and the compressive stresses in the inner tip of the fold makes the thickness of the folded area huge. When manufacturing a dressing, especially when manufacturing a dressing having a thin layer of adhesive, this huge fold with a huge thickness will create a stepwise change of the thickness in the adhesive material, because the adhesive material will be forced to flow to each side of the line of bending of the two flaps, resulting in a local reduced thickness of the adhesive layer. This tendency is even more outspoken when the dressing during manufacturing is subjected pressure in order to obtain bevelled edges along the periphery.
The presence of the wide area with the air channel is followed by a numerous inconveniences. The adhesiveness of the adhesive layer is generally known to be reduced when the adhesive layer is exposed to air. During manufacture ,the edges of a dressing are often bevelled in a process applying pressure and optionally heat. When performing this bevelling process on a conventional dressing with a wide area with the air channel, the adhesiveness of the area with the air channel have been seen to be remarkably reduced. This reduction is probably caused by accelerated oxidation due to the heat, but may also be affected by aqueous vapor, small fibres and dust in general present in the surroundings.
Further, the air channel allows more aqueous vapor and dust, e.g. from printed instructions being present in the package to come into contact with the adhesive layer during storage. It is a known and used feature in wound dressing technology that liquids, e.g., wound exudate will reduce the adhesiveness of the adhesive layer during use of the dressing. But, having a wide area with reduced adhesiveness on a fresh dressing will cause problems with the adhesive when applying it.
When applying a dressing having a wide area with an air channel on a patient's skin the dressing will have a tendency to detach. This can cause a serious problem in case of open wounds where the imperviousness of the dressing is important because of the risk of infecting the wound. A dressing having a wide area with a channel of air could form a weak point for a leakage of exudate in case of a suppurating wound.
In case of a dressing having a very thin layer of adhesive the problem of a stepwise change of the thickness creating a locally reduced thickness is even more pronounced. The problem of the area with the air channel is especially serious in case of small dressings, e.g., for blisters or corns because the fraction of area covered by the air channel compared to the remains of the dressing is greater for these small dressings. In this case the dressing could loose the grip after a shorter period of time.